AGU Blogosphere

Variety of content related to geology, AGU, and academia
https://blogs.agu.org/

Bradshaw Foundation - Rock Art Network

Main site twitter : @BradshawFND
There is some beautiful petrology here, catagorized nicely, but navigation is not fantastic.
I would recommend starting with the index link below.
http://www.bradshawfoundation.com/rockartnetwork/index.php

Geology Page

Authors are: @geologypage on Twitter | geologypage on Facebook
This site has a wonderful blog, with a working search latest news, videos, links to geology software, minerals lists, GEO courses, maps & more
https://www.geologypage.com/